Solaris Tunable Parameters Reference Manual



Number of pages reserved for the exclusive use of the pageout or scheduler threads. When available memory is less than this value, non-blocking allocations are denied for any processes other than pageout or the scheduler. Pageout needs to have a small pool of memory for its use so it can allocate the data structures necessary to do the I/O for writing a page to its backing store. This variable was introduced in the Solaris 2.6 release to ensure that the system would be able to perform a pageout operation in the face of the most severe memory shortage.

Data Type

Unsigned integer


throttlefree / 2


The minimum value is 64 Kbytes or 1/512th of physical memory, whichever is greater, expressed as pages using the page size returned by getpagesize(3C).

The maximum is the number of physical memory pages. The maximum value should be no more than 2% of physical memory. The system does no enforcement of this range other than that described in the Validation section.




Yes, unless dynamic reconfiguration operations that add or delete memory occur. At that point, the value is reset to whatever was provided in the /etc/system file or was calculated from the new physical memory value.


If pageout_reserve is greater than throttlefree / 2, pageout_reserve is set to throttlefree / 2. No message is displayed.


The relationship of cachefree is greater than or equal to lotsfree, which is greater than desfree, which is greater than minfree, which is greater than or equal to throttlefree, should be maintained at all times.

When to Change

The default value is generally adequate. For systems with relatively static workloads and large amounts of memory, adjust this value downwards. The minimum acceptable value is 64 Kbytes expressed as pages using the page size returned by getpagesize(3C).

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